Canon G9X Optics

Zoom
Limited 3x optical zoom ratio, but with decent far-field performance for its class.

The Canon G9X's 3x optical zoom lens covers the equivalent of about 28-84mm on a 35mm camera. That's a fairly limited zoom ratio and not as wide as most compacts go these days, but that's how Canon kept the G9X's size so small. Maximum aperture varies from a pretty fast f/2.0 at wide angle to a somewhat slow f/4.9 at full telephoto.

The following table reflects the maximum and minimum apertures as reported by the camera:

Sharpness and contrast are actually not bad across much of the frame at maximum wide angle and f/5.6, though corners show some softness because of the strong distortion correction applied (see below). Little chromatic aberration is visible as it is effectively suppressed in JPEGs, though some minor flare is evident around the bright white elements of this shot. At medium focal length (~50mm eq.), far-field performance appears to be quite good at f/5.6 with excellent sharpness and contrast, and although some CA is visible, it's still fairly well controlled. Results at full telephoto and f/5.6 are quite good, with good sharpness and contrast across the frame. Again, chromatic aberration is low because the G9X suppresses it in JPEGs.

The G9X also offers digital zoom up to 4x, and what Canon calls a "digital teleconverter" at preset magnifications of 1.6x and 2.0x which can be used at any optical focal length. We've included images using those modes above, since optical zoom ratio is limited.

See below for our studio test shots.

Macro
About average size macro area, with very good detail in the center. Flash overexposed and is partially blocked by the lens at closest focus.

The Canon G9X's lens captured an average size minimum area of 2.78 x 1.85 inches (71 x 47 millimeters). Sharpness is very good in the central area of the frame, though corners and edges are quite soft from field curvature. (Most cameras have some softening in the corners in macro mode.) The Canon G9X's built-in flash is partially blocked by the lens at closest focus distance, resulting in a very dark shadow in the bottom right and overexposure in the top left. You'll likely want to use external lighting for close macro shots with the G9X.

Distortion
Very low to moderately low distortion in JPEGs; very high at wide angle in uncorrected RAW files.

JPEG: The Canon G9X's JPEGs show less than 0.1% of wavy complex distortion at wide angle, a sure sign of in-camera correction (see below). The nearly 0.4% barrel distortion at the telephoto end is moderately low and not the pincushion type of distortion we normally see at telephoto. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide angle) or inward (like a pincushion -- usually at telephoto).

Uncorrected RAW: When converting RAW files using RawDigger (no corrections applied), we see that actual barrel distortion at wide angle is extremely high, at about 4.2%. Uncorrected distortion at full telephoto is still about 0.4% barrel, so the in-camera JPEG wasn't corrected for geometric distortion a full telephoto. Canon's bundled Digital Photo Professional and Adobe Camera Raw automatically correct for geometric distortion, yielding distortion measurements similar to in-camera JPEGs.

High distortion is quite common at wide angle in smaller lenses these days, and most raw converters will automatically correct for it. There is however going to be a loss of resolution as well as possible interpolation artifacts as a result of such strong correction, because pixels in the corners of the frame are being "stretched" to correct for the distortion. And it's not just the extreme corners as the G9X's sensor captures much more than the viewfinder shows requiring significant cropping and interpolation back to full 20-megapixel image dimensions. If you look closely at the corners in the G9X's wide-angle JPEGs, they are not only soft but detail is a little rough with straight edges in the resolution target looking jagged. Obviously, a lens that doesn't require so much correction and is also sharp in the corners to begin with would be preferable, but relaxing constraints on distortion brings other benefits in the lens design, such as a very compact, lower-cost design.

Chromatic Aberration and Corner Softness
CA is low to moderately low at wide angle, and lower at telephoto in JPEGs. Mild to moderate blurring in the corners of the frame at wide angle, but good corner sharpness at full telephoto.

Chromatic Aberration. Lateral chromatic aberration is moderately low in the corners at wide angle at maximum aperture, with some wide but faint purple fringing, and there's very little CA in the center. At full telephoto wide open, lateral chromatic aberration is low in the corners, and very low in the center. See below for examples of uncorrected C.A. Chromatic aberration is a type of distortion visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.

Corner Softness. The Canon G9X's lens produces moderately soft corners at full wide angle when wide open. Blurring is about the same in all for corners and some softness extends fairly deep into the frame, but the center is quite sharp. Rough edges and much of the softness are due to the strong geometric distortion and CA correction taking place at wide angle. Corners at full telephoto are fairly sharp but not as contrasty as the center with clear signs of CA suppression, while the center is sharp.

Corner Shading. Vignetting is fairly low at either end of the zoom, even wide open.

F5.6. When the lens is stopped-down to f/5.6, sharpness actually degraded a bit at wide angle, although contrast improved and CA levels were a little lower. At full telephoto, performance remained about the same at f/5.6 which is to say quite good across the entire frame, as the aperture didn't change very much (wide-open is f/4.9). Vignetting is not significant at either end of the zoom range.

Chromatic Aberration Correction

Unsurprisingly, chromatic aberrations are much higher in uncorrected RAW files than in camera JPEGs. As you can see, the Canon G9X's DIGIC 6 image processor does a pretty good job suppressing most of the lateral chromatic aberration in JPEGs (crops on the left) versus RAW files converted in RawDigger (on the right), which does not correct for CA. Note that most commercial converters like Adobe Camera Raw will automatically correct for CA, as the G9X's .CR2 RAW files have a built-in lens profile.

Overall, not a bad performance for such a compact lens coupled to 1"-type sensor, however optical zoom range is rather limited and there are inevitable tradeoffs at wide angle which need a lot of digital correction. Note that we did not run into the "localized flare issue" at wide apertures we reported on with the G7X and G1X II.

Coverage
Very good accuracy from the LCD monitor.

The Canon PowerShot G9X's LCD monitor displayed very good coverage accuracy in record mode, showing very close to 100% coverage at wide angle, and about 99% coverage at full telephoto.